1. Field of the Art
This invention relates to a novel .beta.-lactam antimicrobial agent and pharmaceutically acceptable salts thereof. In more detailed description, this invention relates to novel cephem compounds, pharmaceutically acceptable salts thereof and the process for preparing them, and relates further to an antimicrobial agent comprising the compound as an effective component. The compounds are useful as medical agents and animal drugs since they have an excellent effect on the therapy for diseases of human and other animals caused by pathogenic bacteria.
2. Related art
Cephem compounds which are structurally relative to the compounds of the present invention, for example, have been disclosed in Japanese patent Laid-Open Publication Nos. 124790/1980, 122388/1981 and 76083/1984. In addition, we have already discovered cephem compounds which are structurally relative to the compounds of the present invention and disclosed in Japanese patent Laid-Open Publication Nos. 178991/1986, 19593/1987 and 205088/1987 (These compounds have also the same substituted vinyl side chain as those of the compounds of this present invention (described in detail later) However, the compounds of the present invention are novel cephem compounds having a different substituent at the side chain from those of these known relative compounds)
Since cephalosporin antibiotics have a wide antimicrobial activity for Gram-positive and negative bacteria, various semi-synthesized cephalosporin compounds have already been prepared commercially and used clinically as therapeutic medicines for various infectious diseases. However, only a few among these medicines have an antimicrobial activity for Pseudomonas aeruginosa and Myxomycetes, and many of these medicines are unstable for .beta.-lactamase produced by the resistant strain. Thus, these medicines have a defect that they have a low antimicrobial activity for the resistant strain, proposing a clinical problem (W. E. Wick., Chapter 11 in "Cephalosporins and Penicillins, Chemistry and Biology", edited by E. H. Flynn, Academic Press, New York, N.Y., 1972, ).